Oscillator



Aug. 21, 1945. I s BEAUDOIN 2,382,954

OS C ILLATOR Filed Nov. 10, 1943 v 365M)?! v Patented Aug. 21, 1945 STATES PATENT OFFICE 2,382,954 s oscmLA'roR Serge Beaudoin, St. Joseph, Quebec, Canada Application November 10, 1943, Serial No. 509,721

6 Claims. (Cl. 250-36) The present invention pertains to a novel vacuum tube oscillator. The principal object is to provide an oscillator of improved frequency stability. v

This object is accomplished by meansof a pair of inductively coupled coils, of equal inductance connected respectively to the cathode and grid and without forming a parallel circuit with the tube. The manner in which the device functions to produce the desired result is set forth in the following description.

The invention is fully disclosed by way of example in the following description and in the accompanying drawing in which:

Figures 2 and 3 are diagrams of three different circuits according to the invention. j

Reference to these views will now be made by use of like characters which are employed to designate corresponding parts throughout.

In Figure l is shown a pentode I including a cathode 2, and anode 3 and three grids 4, 5 and I5. The anode, cathode and grids may be charged in any suitable manner. For example, the anode 3 and grid 5 are connected to positive potentials I and 8. Connected to the grid 5 is a bleeder comprising a series resistor I with a shunt condenser II, the resistor being grounded at I2 and tapped at I3.

The grid 4 is grounded at I3. The grid 6 is connected as will presently be described.

Oscillation is produced through a pair of inductively coupled coils I4, l5 of equal inductance and connected respectively to the cathode 2 and the grid 6 at I! and I8. In the connection I8 may be provided a grid leak consisting of a series condenser I9 and a shunt resistor 20. Both coils are grounded at 2| and 50, and the coil I4 may be connected in series to a resistor 22 having a shunt condenser 23 for polarization of thegrid through the cathode.

Coupled to the coils I4, I5 at the connections I1, I8 are a pair of ganged or synchronized variable condensers 24, 25 having equal capacity and ghe same charging curve. Both are grounded at In operation, the oscillation is maintained by the cathode and acts on the grid through the self-inductances. The cathode-grid oscillation being in tune, the tube will oscillatenat a frequency determined by the inductances. This oscillator has a much higher stability than the con ventional oscillators, such as the, Hartley circuit. The higher stability is attributed to the series, rather than parallel, relation of the inductances to the tube. Further, the variations in the cafeeding variations.

pacity of the several electrodes relatively to the chassis, caused by voltage variations applied to these electrodes, do not influence the inductances. Since the latter control the frequency of oscillation, the oscillation remains stable in spite of For a greater efficiency, the polarization device 22, 23 is used as shown in Figures 1 and 2.

In the embodiment shown in Figure 2, the polarization device has been eliminated, and both inductance coils 32, 33 are connected to a common ground 34. This device lends itself more readily to change of band.

Figure 3 shows a triode with a cathode 35, plate 36 and grid 31. The inductance coils 42, 43 have a common ground 44, and the ganged condensers 45, 46 are connected in parallel respectively with the coils.

The stability of oscillation isdue mostly by the inductance of the cathode which is in series with the tube.

In stability of oscillation, this system compares favorably with the crystal and has the advantage of a variable frequency. The change of frequency requires a two-circuit switch, however the device is no more complicated than, for example, the Hartley circuit.

Although specific embodiments of the invention have been illustrated and described, it will be understood that various alterations in the details of construction may be made without departing from the scope of the invention as indicated by the appended claims.

What I claim as my invention is:

1. In an oscillating circuit, .a vacuum tube having a cathode, an anode and a grid, 3. pair of inductively coupled coils of equal inductance connected respectively to said cathode and grid at ductively coupled coils of equal inductance connected respectively to said cathode and grid at one end and grounded at the other end, and a pair of ganged condensers connected respectively to said coils, and a polarization device connected to said cathode.

4. In an oscillating circuit, a vacuum tube having a cathode, an anode and a grid, a pair of inductively coupled coils of equal inductance connected respectively to said cathode and grid at one end grounded at the other end, and a pair of ganged condensers connected respectively in parallel with said coils, and a polarization device connected to said cathode.

5. In an oscillating circuit, a vacuum tube having a cathode, an anode and a grid, a pair of inductively coupled coils of equal inductance connected respectively to said cathode and grid at one end and grounded at the other end, and a pair of ganged condensers connected respectively to said coils, a resistor in series with one of said coils, and a condenser in parallel with said resistor.

6. In an oscillating circuit, a vacuum tube having a cathode, an anode and a grid, a pair of inductively coupled coils of equal inductance connected respectively to said cathode and grid at one end and grounded at the other end, and a pair of ganged condensers connected respectively to said coils, and a grid leak between said grid and one of said coils.

SERGE BEAUDOIN. 

